The relationship between people and harp seals is slowly changing. For years, newborn pups were killed in large numbers for their gorgeous white coats. That still happens, but tourists are visiting some of the haul-out sites where the seals give birth, inhibiting the slaughter and also providing an economic reason not to kill the pups. Harp seal pups grow at an astonishing rate on the fat-rich milk produced by their mothers. From a birth weight of about 10 kg, they bulk up to 35 kg in 10 days. This gets them ready quickly for an 11 month, 5,000 km swim to the far corners of their Arctic range and back again. Large groups swim together, leaping, rolling, and porpoising. Adults have a dark, harp-shaped pattern on their fur.